feat(File): add modification status constants and property

Add DocMDP modification tracking to File entity:
- MODIFICATION_UNCHECKED (0): Not yet checked
- MODIFICATION_UNMODIFIED (1): No modifications detected
- MODIFICATION_ALLOWED (2): Modifications within DocMDP permissions
- MODIFICATION_VIOLATION (3): Unauthorized modifications detected

Add modificationStatus property (SMALLINT) to track PDF modification state
after signature validation.

Signed-off-by: Vitor Mattos <[email protected]>

Author: vitormattos

lib/Db/File.php

@@ -36,6 +36,8 @@
  * @method int getStatus()
  * @method void setMetadata(array $metadata)
  * @method ?array getMetadata()
+ * @method void setModificationStatus(int $modificationStatus)
+ * @method int getModificationStatus()
  */
 class File extends Entity {
 	protected int $nodeId = 0;
@@ -49,13 +51,19 @@ class File extends Entity {
 	protected ?string $signedHash = null;
 	protected ?string $callback = null;
 	protected ?array $metadata = null;
+	protected int $modificationStatus = 0;
 	public const STATUS_NOT_LIBRESIGN_FILE = -1;
 	public const STATUS_DRAFT = 0;
 	public const STATUS_ABLE_TO_SIGN = 1;
 	public const STATUS_PARTIAL_SIGNED = 2;
 	public const STATUS_SIGNED = 3;
 	public const STATUS_DELETED = 4;
 
+	public const MODIFICATION_UNCHECKED = 0;
+	public const MODIFICATION_UNMODIFIED = 1;
+	public const MODIFICATION_ALLOWED = 2;
+	public const MODIFICATION_VIOLATION = 3;
+
 	public function __construct() {
 		$this->addType('id', Types::INTEGER);
 		$this->addType('nodeId', Types::INTEGER);
@@ -69,6 +77,7 @@ public function __construct() {
 		$this->addType('callback', Types::STRING);
 		$this->addType('status', Types::INTEGER);
 		$this->addType('metadata', Types::JSON);
+		$this->addType('modificationStatus', Types::SMALLINT);
 	}
 
 	public function isDeletedAccount(): bool {

lib/Migration/Version14000Date20251206120000.php

@@ -0,0 +1,41 @@
+<?php
+
+declare(strict_types=1);
+/**
+ * SPDX-FileCopyrightText: 2025 LibreCode coop and contributors
+ * SPDX-License-Identifier: AGPL-3.0-or-later
+ */
+
+namespace OCA\Libresign\Migration;
+
+use Closure;
+use OCP\DB\ISchemaWrapper;
+use OCP\DB\Types;
+use OCP\Migration\IOutput;
+use OCP\Migration\SimpleMigrationStep;
+
+class Version14000Date20251206120000 extends SimpleMigrationStep {
+	/**
+	 * @param IOutput $output
+	 * @param Closure(): ISchemaWrapper $schemaClosure
+	 * @param array $options
+	 * @return null|ISchemaWrapper
+	 */
+	#[\Override]
+	public function changeSchema(IOutput $output, Closure $schemaClosure, array $options): ?ISchemaWrapper {
+		/** @var ISchemaWrapper $schema */
+		$schema = $schemaClosure();
+		$table = $schema->getTable('libresign_file');
+
+		if (!$table->hasColumn('modification_status')) {
+			$table->addColumn('modification_status', Types::SMALLINT, [
+				'notnull' => true,
+				'default' => 0,
+				'comment' => 'DocMDP modification detection status: 0=unchecked, 1=unmodified, 2=allowed, 3=violation',
+			]);
+			return $schema;
+		}
+
+		return null;
+	}
+}